INT-2888 Fix MapToObjectTransformerParser CL Issue

In the parent-child environment configuration that relies on class names may produce
a `ClassNotFoundException`.

* remove usage of `ClassLoader` in the `MapToObjectTransformerParser` and allow to use the `ConversionService` from application context
* remove deprecation from `MapToObjectTransformer`
* refactor `MapToObjectTransformer` to use `IntegrationObjectSupport#getConversionService()`
* remove fallback to the `beanFactory#getConversionService()` in the `ExpressionUtils`

JIRA: https://jira.springsource.org/browse/INT-2888

INT-2928: Do Not Fallback to BF's ConversionService

* Polishing according PR's comments
* Important note about `conversionService` & `integrationConversionService` beans
* Link a JIRA about elimination of `BeanFactory`'s `ConversionService` usage
* Add a note to the 2.2-3.0 Migration Guide

JIRA: https://jira.springsource.org/browse/INT-2928

INT-2888 Doc Polishing
Merge pull request #722 from artembilan/INT-2888